the problem with text is it can be taken in the wrong way, and making jokes in it can be interpreted in so many different ways, there is no emotional sub-communication to what is being communicated and no tonality to judge the way in which it was said, if she interpreted your comment as serious sarcasm, then you probably came off as a dick, instead of funny,
I assume you don't have too much rapport with this girl judging by how she is reacting, continueing to break rapport on her probably won't go very well, you should just be a little bit more playful and open make her comfortable instead of busting on her, then when she is comfortable you can tease a bit,
next time you get challenged like that, just challenge her back
You: There are quite a few fucking adorable people. What makes you unique is your modesty
Her:really?
You: Why not?
1. it wasn't that your opener was showing too much interest basicly it seems like it translates into, WOW YOU THINK YOUR FUCKING GREAT DON'T YOU?
2. you can't really assume that
3. see above about breaking rapport, just do something more like,

you changed your cute sign, I liked that pic